Canned motor pumps are widely used to circulate water in heating and plumbing systems. Examples of canned motor pumps are found in U.S. Pat. Nos. 4,990,068 and 5,549,459. Canned motor pumps are lubricated by the fluid being pumped which typically is water. These pumps are commonly referred to as water lubricated pumps. The pumps are typically driven by an electric motor and the rotor of the motor, as well as the pump impeller, are mounted on a common shaft. An inherent feature of canned motor pumps is that all rotating parts are immersed in the fluid being pumped. Because of that they generally do not require any dynamic seals such as packings or mechanical seals. Since the shaft is immersed in the fluid being pumped, it follow that the bearings supporting the shaft are also immersed in the fluid, usually water. It is a common practice to use sleeve bearings, as opposed to ball bearings, in canned motor pumps. To prevent the fluid from flooding the motor stator, there is provided a thin wall tube that is disposed between the stator and rotor. This thin walled tube is commonly referred to as a sleeve.
Two of the desirable features that canned motor pumps should have are (1) good alignment of components and (2) field serviceability. Pumps currently on the market are either field serviceable but have potentially poor alignment, while others provide proper alignment but are not readily field serviceable. The objective of the present invention is to provide a motor pump, particularly a canned motor pump, which is characterized by proper alignment between pump components, as well as the ability to be easily serviced in the field.